Recently, in communication systems, higher service frequency bands are increasingly used and cells tend to become gradually smaller in order to accommodate or handle high speed communication and more traffic, so the use of the existing centralized cellular radio network scheme as it involves many problems. Namely, because locations of base stations are fixed, flexibility in configuring radio links is degraded, making it difficult to provide an effective communication service in a radio environment in which a traffic distribution or a traffic demand changes severely.
In an effort to solve the problem, a relay system has been proposed. The relay system is advantageous in that a partial shadow area generated in a cell coverage is covered to extend a cell service coverage, a system capacity can be increased, and the use of a relay node in an initial situation in which a service request is scarce reduces the burden of initial installation costs.
The relay node in the relay system serves as a fixed or mobile small base station to substantially extend a system capacity and a service area of a base station. In particular, in case of the mobile relay node, a terminal may serve as a relay node to relay a communication service between an adjacent terminal located outside the service area of the base station or located in a shadow area and the base station.
However, when the terminal serves as a relay node, resource for exchanging data with the adjacent terminal is additionally required and a signal interference problem arises with other base station or a nearby terminal.